Question

Write a note on vulcanization of rubber.

Answer 1

1. Natural rubber is very soft and brisk. it has a high water absorption capacity and low tensile strength. Its properties can be improved by a process called vulcanization.

2. Natural rubber is mixed with 3-5% sulphur and heated at 100-150°C causes cross-linking of the cis-1, 4 polyisoprene chains through disulphide (– S – S –) bonds.

3. The physical properties of rubber can be altered by controlling the amount of sulphur that is used for vulcanization. When 3 to 10% sulphur is used the resultant rubber is somewhat harder but flexible.

4. Following properties of rubber CH₃

Improved by vulcanization:

• Tensile strength
• Elasticity
• Hardness
• Tear strength
• Resistance to solvents

   Structure of Vulcanized rubber